Solar heated devices in which gas is heated and expanded by sunlight have been proposed previously; for example, in U.S. Pat. No. 3,436,908--VanDelic. Other background solar devices are described in U.S. Pat. Nos. 1,814,897--Coxe and 3,490,996--Kelly. There is a need for improvement of such solar devices, especially in view of present shortages of economical fuels for electric power generating systems.